Answer:
x = 7.5 km/h
Step-by-step explanation:
• First calculate the distance covered by walking at 3 km/h for 45 minutes ( 0.75 h):
distance = speed × time
= 3 × 0.75
= 2.25 km
• Therefore, she covered 2.25 km of the total journey by walking. Since she was 6 km from the starting point at the end of the entire journey, we can calculate the distance remaining, which she had to run:
distance she had to run = 6 - 2.25
= 3.75 km
• Now we can calculate the speed of the 30 minute (0.5 h) run:
speed = distance ÷ time
= 3.75 ÷ 0.5
= 7.5 km/h
This means that she ran at 7.5 km/h for half an hour.
∴ x = 7.5
